如何在MySQL中创建具有N:M关系的表? [英] How to create tables with N:M relationship in MySQL?

问题描述

比方说，我有两个表:商店和产品.我希望我的商店有产品清单.我该怎么办?

Let's say I have this two tables: Store and Product. I want my store to have a list of products. How can I do that?

create table store(
id int unsigned not null auto_increment,
store_name varchar(30) not null,
product_list_FK int unsigned not null,
primary key(id)
);

create table product(
id int unsigned not null auto_increment,
product_name varchar(30) not null,
price float not null,
primary key(id)
);

我开始了类似的事情，但是我不知道该如何完成，你们能帮我吗?

I started something like that, but I don't know how to finish, can you guys help me?

推荐答案

多对一(产品只能有一家商店)

Many-to-one (products can only have one store)

create table store(
    id int unsigned not null auto_increment,
    store_name varchar(30) not null,
    primary key(id)
);

Query OK, 0 rows affected (0.02 sec)

create table product(
    id int unsigned not null auto_increment,
    store_id int unsigned not null,
    product_name varchar(30) not null,
    price float not null,
    primary key(id),
    constraint product_store foreign key (store_id) references store(id)
);

Query OK, 0 rows affected (0.02 sec)

多对多(产品可以在许多商店中购买)

Many-to-many (products can be in many stores)

create table store(
    id int unsigned not null auto_increment,
    store_name varchar(30) not null,
    primary key(id)
);

Query OK, 0 rows affected (0.04 sec)

create table product(
    id int unsigned not null auto_increment,
    store_id int unsigned not null,
    product_name varchar(30) not null,
    price float not null,
    primary key(id)
);

Query OK, 0 rows affected (0.01 sec)

create table product_store (
    product_id int unsigned not null,
    store_id int unsigned not null,
    CONSTRAINT product_store_store foreign key (store_id) references store(id),
    CONSTRAINT product_store_product foreign key (product_id) references product(id),
    CONSTRAINT product_store_unique UNIQUE (product_id, store_id)
)

Query OK, 0 rows affected (0.02 sec)

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